That is such a tough decision,and I no not envy you,the task of making it.
That why I ahve 11 Cats,as I could never let one go,until Pouncette,and Ragnar,had places to go where they would be the Boss Cat.
And Angel,may be beeter off,with Flutters Sisters,and you will be able,to svae the life of another Kitten,who has no other place to go.
May our Lord,give you strngth,it will not be easy,but it may be for the best.